CHANGE IN PHASE COMPOSITION, MORPHOLOGICAL CHARACTERISTICS, AND NON-FARADAY CAPACITY INDICATORS OF ZINC OXIDE AFTER HEAT TREATMENT IN A CITRIC ACID ENVIRONMENT

• Datum: 2025
• Hauptverfasser: Panteleimonov, Radyslav, Pershina, Katherine, Lisnycha, Tetyana, Riabokin, Oleg
• Format: Artikel
• Sprache: English
• Veröffentlicht: V.I.Vernadsky Institute of General and Inorganic Chemistry 2025
• Online Zugang: https://ucj.org.ua/index.php/journal/article/view/744
• Назва журналу: Ukrainian Chemistry Journal

The conditions for changing the phase composition and non-Faraday capacitance in zinc oxide samples with different surface morpho­logy after melting in a citric acid environment were established using X-ray phase analysis, porometry, scanning electron microscopy, and electrochemical impedance spectroscopy methods. The effect of the mass ratio of zinc oxide and citric acid on the growth rate of certain wurtzite orientations and the appearance of anisotropic phases, which lead to a decrease in the specific surface area of ​​the samples, was established. An increase in the concentration of citric acid leads to the appearance of two types of particles: large conglomerates with submicron sizes and small particles less than 100 nm in size, which aggregate on the surface of larger particles. Heat treatment in a citric acid environment of ZnO leads to a 10-fold increase in active resistance with a 107-fold loss of non-Faraday capacitance. It is proven that the decrease in the values ​​of non-Faraday capacitance correlates with the mass ratio of ZnO: C6H8O7. At a mass ratio of 1:2 relative to 1:1, the non-Faraday capacitance decreases by 2 orders of magnitude. The reason for the new formations with increasing concentration can be considered as a consequence of corresponding changes in the deeper microstructure. SEI studies have proven the relationship between the change in the surface morphology of the samples, the indicators of active resistance and non-Faraday capacitance of zinc oxide samples. The electrochemical impedance spectra of the samples have all the features of a blocked porous electrode, in which there is no Faraday current. It is shown that the presence of polycrystalline structures leads to the appearance of an additional semicircle in the region of 108 Hz and a change in the equivalent electrochemical scheme, which is a sign of the ability of surface structures to diffuse defects on the surface of polycrystals.